This invention relates generally to dental measurement instruments and more particularly to a dental probe for measuring the distance from the gum tissue surface to the jawbone which is supporting an implant.
When a tooth has severe nerve damage or is totally edentulous, a dentist will often replace the damaged tooth with an implant. In preparing the patient for receipt of an implant, an insert is positioned into the jawbone. Placing the insert inside the bone involves cutting the gum tissue above the area where the implant will be placed, drilling into the jawbone, and screwing the insert into the jawbone. Typically, a secondary healing cap is placed over the insert to maintain the opening through the gum tissue. The secondary healing cap allows gum tissue to heal until prosthetic fabrication can be completed.
After the gum tissue heals, the surgeon will replace the secondary healing cap with an abutment. The abutment is typically a circular structure which screws into the implant. The abutment radius is approximately the same radius as the secondary healing cap. The abutment height should equal the distance between the gum tissue surface and the jawbone.
Because the height of the gum tissue varies depending on the individual patient and upon the position in the patient's mouth, abutment size must also vary. The abutment size refers to the height of the abutment. Standard abutments come in sizes which vary in 1.0 millimeter (0.039 inch) increments. Thus a dentist may choose a 2.0 millimeter or 3.0 millimeter abutment, but not a 2.5 millimeter abutment.
Most dentists simply guess the height of the patient's gum tissue in size trying to determine the correct abutment size. Other dentists try to obtain a more accurate measurement by using currently available dental probes to measure gum tissue height. Using currently available dental probes is problematic since they are typically not designed to measure the distance from the gum tissue surface to the jawbone. For example, U.S. Pat. Nos. 4,340,069, 4,364,730, and 4,768,952 disclose dental probes designed to measure the height of a periodontal cavity, and in particular, how far the periodontal cavity extends beyond the boundary between the tooth enamel and the root cementum. U.S. Pat. No. 1,586,302 discloses a specialized dental probe designed to dispense medication into a periodontal cavity. U.S. Pat. Nos. 3,559,292, 904,990 and 3,388,473 disclose dental probes designed for probing and measuring the distance of the cavity inside the tooth and its root canal.
Using the aforementioned dental probes for measuring the gum tissue height to determine the correct abutment size is often difficult and sometimes inaccurate. One problem with currently available dental probes is that the probe tips are typically circular in cross section. In measuring the gum tissue height, the tip of the dental probe is inserted in the juncture between the gum tissue and the secondary healing cap. Thus, the gum tissue height is measured on the side of the probe tip furthest away from the secondary healing cap. Since the distance between the tip of the probe and the wall of the secondary healing cap is equal to the radius of the probe at its widest point, the measurement of gum tissue height is not made at the exact location where the abutment is to be placed, but at a location which is a probe tip circumference away from the secondary healing cap. Furthermore, because the probe tip is circular, the curvature of the probe tip does not fit the curvature of the secondary healing cap sidewalls. Thus the probe tip is prone to slippage or misalignment which can lead to inaccuracies in measurement.
Another problem with using currently available dental probes is inaccuracy caused by gum tissue movement. Inserting the probe tip into the juncture between the secondary healing cap and gum tissue displaces gum tissue. Because the secondary healing cap is firmly implanted into the jaw bone, tissue movement next to the probe tip causes gum tissue to bunch up around the probe tip increasing gum tissue height. An increase gum tissue height measurement leads to inaccurate abutment height measurement.
Using currently available dental probes to measure gum tissue height is difficult, thus making selection of an incorrect abutment size likely. Choosing the wrong abutment size increases the time spent on and the expense associated with the abutment placement or replacement procedure. Considerable time is added to the procedure since the dentist must take the time necessary to redo the procedure. The dentist must remove the incorrectly sized abutment, remeasure a new abutment, and put on a new abutment. In addition, material costs are increased. The incorrectly sized abutment must either be thrown away, adding to material costs, or resterilized to be used in another patient procedure. An alternative method of determining the correct abutment size is needed.